12.1- GLYCOLYSIS

Question 1

What are the two types of cellular respiration?

Answer 1

aerobic respiration

anaerobic respiration

Question 2

What is aerobic respiration and what does it produce?

Answer 2

requires oxygen + produces CO2, water and much ATP

Question 3

What conditions does anaerobic respiration occur in, and what is produced?

Answer 3

takes place in absence of oxygen + produces lactate (in animals) or ethanol + CO2 (in plants + fungi) but only little ATP in both cases

Question 4

What four stages can aerobic respiration be divided into?

Answer 4

1. glycolysis
2. link reaction
3. Krebs cycle
4. oxidative phosphorylation

Question 5

What is glycolysis?

Answer 5

splitting of 6-carbon glucose molecule into two 3-carbon pyruvate molecules

Question 6

What is the link reaction?

Answer 6

3-carbon pyruvate molecules enter into series of reactions which lead to formation of acetylcoenzyme A, a 2-carbon molecule

Question 7

What is the Krebs cycle?

Answer 7

introduction of acetylcoenzyme A into cycle of oxidation-reduction reactions that yield some ATP + a large quantity of reduced NAD + FAD

Question 8

What is oxidative phosphorylation?

Answer 8

use of electrons, associated with reduced NAD + FAD, released from Krebs cycle to synthesise ATP with water produced as by-product

Question 9

What is the initial stage of aerobic + anaerobic respiration?

Answer 9

glycolysis

Question 10

Where does glycolysis occur?

Answer 10

in cytoplasm of all living cells

Question 11

What stages can glycolysis be broken down into? (4)

Answer 11

phosphorylation of glucose to glucose pyruvate

splitting of phosphorylated glucose

oxidation of triose phosphate

production of ATP

Question 12

Glycolysis- phosphorylation of glucose to glucose phosphate #1

Answer 12

glucose must first be made more reactive by addition of two phosphate molecules

Question 13

Glycolysis- phosphorylation of glucose to glucose phosphate

where do the phosphate molecules come from #2

Answer 13

hydrolysis of two ATP molecules to ADP

this provides energy to activate glucose + lowers activation energy for enzyme-controlled reactions that follow

Question 14

Glycolysis- splitting of phosphorylated glucose

Answer 14

each glucose molecule split into two 3-carbon molecules known as triose phosphate

Question 15

Glycolysis- oxidation of triose phosphate

Answer 15

hydrogen removed from each of two triose phosphate molecules + transferred to hydrogen-carrier molecules known as NAD to form reduced NAD

Question 16

Glycolysis- production of ATP

Answer 16

enzyme-controlled reactions convert each triose phosphate into another 3-carbon molecules called pyruvate
in this process, two molecules of ATP regenerated from ADP

Question 17

What is the overall yield from one glucose molecules undergoing glycolysis? (3)

Answer 17

two molecules of ATP (4 produced but two used up in initial phosphorylation of glucose + so net increase in two molecules)

two molecules of reduced NAD (have potential to drive energy to produce more ATP)

two molecules of pyruvate

Question 18

How does glycolysis provide indirect evidence for evolution?

Answer 18

universal feature of every living organism

Question 19

Where are the enzymes for the glycolytic pathway found?

Answer 19

in cytoplasm of cells + so glycolysis doesn’t require any organelle or membrane for it to happen

Question 20

In the absence of oxygen, what can happen to the pyruvate produced from glycolysis?

Answer 20

can be converted into either lactate or ethanol during anaerobic respiration

Question 21

Why is it necessary that the pyruvate produced from glycolysis can be converted into either lactate or ethanol during anaerobic respiration?

Answer 21

necessary to re-oxidised NAD so glycolysis can continue

Question 22

What is different about the potential energy stored in pyruvate molecules from anaerobic respiration?

Answer 22

yields only small fraction of potential energy stored in pyruvate molecule

Question 23

What do most organisms do to release the remainder energy from the pyruvate molecules from anaerobic respiration?

Answer 23

most organisms use oxygen to break down pyruvate further